80 On the Reductiori of Horse Labour by single Carts. . 



loaded as much above the axle as below, it will equalize itself on 

 every inclination, it will never lose its equilibrium up or down the 

 steepest slope. For this object the wheel should be as high as 

 can be conveniently used. And instead of cranking the axle, 

 which to be sufficiently strong must be heavy and clumsy, I 

 should recommend, as shown in the sketch, the smaller inconve- 

 nience of its passing in its ordinary form through the carriage, 

 suspending the body from it. I think the shape presents a diffi- 

 culty in applying the horse's strength with best advantage, and 

 to overcome it I would boldly propose submitting to another in- 

 convenience in the inside of the carriage, viz., a chain attached to 

 the middle of the axle-tree and to a whipper," with or without 

 a slight iron support fixed to the centre of the " fore-shutlock." 

 A moveable midland ''side-ladder" would be sufficient to protect 

 the wheel when a load was raised above it. 



Fig. 6 explains (see H H N N) the above position, as well as 

 embodies the principles advocated in regard to pressure. And it 

 is also intended to exhibit in a combined view four methods of 

 carrying a load on two wheels, with the degree of pressure in 

 each. And I trust I may be excused some recapitulation in the 

 description of it. 



C G C C is a given bulk on a short cart. HH HH is the same 

 quantity on a carriage three times the length. NNNN is a car- 

 riage of similar length and contents loaded below the axletree. 

 H H N N combines the two long loads, and is intended to ex- 

 hibit the effect of a bulk, equal above and below the axle. 

 E the plumb-line to the axle, shows what portion of each bulk 

 has passed off the equilibrium and become pressure. B a line 

 through the axle at right angles with the incHned plane, traverses 

 the middle of each portion of pressure ; while e marks the centre 

 of gravity of each pressure. This centre of pressure is traced on 

 its arc to its resting point at o, on the levers D A, which point 

 determines what is received respectively by the horse and the 

 wheel ; by the rule that the share borne by each is exactly in 

 inverse proportion to their distance from the point of pressure. 



In the high, narrow-based bulk C C C C, the area of pressure 

 is found in the pentagon D C C, the centre of its gravity at e e e, 

 and the arc described from thence to the lever DA a, at o o, 

 determines the point which will give the relative portion of pres- 

 sure sustained by D, and by A a the bearing point on the horse's 

 back. This has been elucidated in Figs. 1 and 2. 



In the bulk HH H H the triangle Dm m shows the area of 

 pressure, and e e its centre, and thence an arc described to o, on 

 the lever D A, exhibits the share of weight borne respectively by 

 D and A. This has been practically shown in Fig. 3. 



\i\N N N N seen the same superficies and the same contents 



